holds for the following two cases: \( v \in {}_0H^\gamma (a,b;\mathcal {X}^*) \)  and
\( w \in {}^0H^\gamma (a,b;\mathcal {X}) \) ; \( {a+}^\gamma v \in L^{2/(1+\gamma )}(a,b;\mathcal {X}^*) \)  and \( {b-}^\gamma v \in L^{2/(1+\gamma )}(a,b;\mathcal {X}) \) . For the above theoretical results, we refer
the reader to [1]}, [2]}.
